diff --git a/src/a2a/utils/proto_utils.py b/src/a2a/utils/proto_utils.py
index 14ac098d..57272c89 100644
--- a/src/a2a/utils/proto_utils.py
+++ b/src/a2a/utils/proto_utils.py
@@ -230,6 +230,8 @@ def task_state(cls, state: types.TaskState) -> a2a_pb2.TaskState:
                 return a2a_pb2.TaskState.TASK_STATE_INPUT_REQUIRED
             case types.TaskState.auth_required:
                 return a2a_pb2.TaskState.TASK_STATE_AUTH_REQUIRED
+            case types.TaskState.rejected:
+                return a2a_pb2.TaskState.TASK_STATE_REJECTED
             case _:
                 return a2a_pb2.TaskState.TASK_STATE_UNSPECIFIED
 
@@ -703,6 +705,8 @@ def task_state(cls, state: a2a_pb2.TaskState) -> types.TaskState:
                 return types.TaskState.input_required
             case a2a_pb2.TaskState.TASK_STATE_AUTH_REQUIRED:
                 return types.TaskState.auth_required
+            case a2a_pb2.TaskState.TASK_STATE_REJECTED:
+                return types.TaskState.rejected
             case _:
                 return types.TaskState.unknown